Various medical devices have been developed which apply electrical stimulation to the tissue of a patient in order to elicit muscle movement or treat a medical condition, including implantable pulse generators and microstimulators. Other medical devices have been developed which monitor electrical characteristics inside the body, such as impedance across a given area, electroneurogram signals, electrocardiogram signals, or electromyogram signals. These devices often use fully implanted or percutaneously implanted medical leads to provide stimulation or sensing at sites throughout a patient's body.
When implanting a medical lead percutaneously, the distal end of the lead is implanted in tissue at the therapy site and the proximal end protrudes through the skin and outside the body. The proximal end of the lead can be connected to an external device, such as an external pulse generator. The external device typically has a connector or lead interface (hereinafter ‘interface’) capable of coupling, temporarily, to the terminal connector of the lead.
An external device may be used during the implantation procedure for a fully implanted lead and implanted medical device. Before the proximal portion of the lead is connected to the implantable medical device and implanted, it can is connected to the external device to determine whether the distal end of the lead is in a position to deliver stimulation to the correct site or to sense the desired signal. This process may involve connecting and disconnecting the interface several times. This can lead to problems when an interface cannot be securely attached and removed, multiple times, quickly and easily.
Some lead implantation procedures use a stiffening wire or a steering stylet. The stiffening wire or steering stylet extends through a lumen running the length of the lead and protrudes from the proximal end of the terminal connector. If an interface cannot accommodate the portion protruding from the lead, then the wire or stylet must be completely removed from the lead. If, upon testing, it is discovered that the lead needs to be moved, the wire or stylet must be reinserted into the lead.
The external device may additionally or alternatively be carried with the patient during a trial period and used to determine whether the therapy will be efficacious before the more onerous and expensive step of connecting to and implanting an implantable medical device is taken, or used during a temporary treatment in which a fully implanted medical device is not desired. Under these circumstances, the lead extends percutaneously to the interface, and the patient keeps the interface and the external device on their person for the duration of the test period, which may be one or more weeks. During this period, the patient goes about their life, exposing the lead, interface, and external device to unpredictable circumstances. If the mechanism engaging the lead in the interface inadvertently moves from the closed position to the open position during this trial period, the connection between the external device and the lead can be lost and the lead can become removed from the interface at unwanted times. On the other hand, if the external device or interface fall or are pulled on, or if the lead is caught on something, the pressure applied to the lead can cause discomfort, pain, or in extreme situations could dislodge the distal end of the lead from the implantation site. Further, a large interface can grow cumbersome or embarrassing to a patient who has to keep the device on their person for extended periods.
Conventional interfaces do not address all the foregoing considerations. Accordingly, there remains a need for improved techniques and systems for temporarily connecting percutaneously implantable medical leads to external devices.